Herman schlundt



UNITED STATES PATENT. OFFICE; I

HERMAN SCHL'UNDT, OF COLUMBIA, MISSOURI.

CONCENTRATIITG RADIUM ORE.

No Drawing.

T 0 all whom it may concern:

Be it known that I, HERMAN SGHLUNDT, a citizen of the United States,residing at C0- lumbia, county of Boone, State of Missouri,

have invented certainnew anduseful Imradium content.

'I have found that the radium in carnotite ores, and certain othersuitable radium containing material such as samarskite, can be greatlyconcentrated by treatment of the ore, in a wet way, with a solvent whichwill dissolve the radium, together with barium, as sulfates, by thenprecipitating the dissolved sulfates in admixture with the un dissolvedmaterial, as by dilution with water, and by subjecting the. resultingproduct containing the precipitated sulfates to a differentialsedimentation, whereby the sulfates are obtained in the form of aconcentrate of relatively high radium content.

The solvent of the radium and barium as sulfates which I have foundofparticular advantage, is hot concentrated sulfuric acid, and theinvention will be described more in detail in connection therewith. Bytreating the radium containing ore with concentrated sulfuric acid,radium, together with the barium, can be dissolved as sulfates andthereby extracted from the main body of the ore. By then diluting theconcentrated sulfuric acid solution with water, the dissolvedradium-barium sulfates canbe pre-' cipitated practically completely in'a fine state ofdivision so that they are of a nature which isparticularly adapted to separation from the gangue constituents of theore by a diflerential sedimentation. i

The nature and advantages of the invention will more clearly appear fromthe following detailed description.

.The powdered carnotite ore, ground or,

pulverized to pass through a ten or 20 mesh sieve, is digested withconcentrated sulfuric Specification of Letters Patent. Patented Aug. 15,1916.

Applicationfiled February 21, 1916. Serial No. 79,758.

acid of about60 Baume or higher, until atemperature of about 200 C. orabove, is reached. The acid may be either crude acid,

or partially refined, or chemically pure. The

quantity of acid'required must be sufficient to wet the ore thoroughly.It may be somewhat less, weight for weight, than the ore, and can, ofcourse, be varied, and will naturally be varied, with different ores.The

gangue constituents of carnotite ores are made up principally of sand.As a result of the digestion with the concentrated sulfuric acid, theradium, together with barium, is extracted as sulfate, so that themixture resulting from the-digestion contains the sulfate in solutionand thereby physically separated from the sand. When allowed to cool,the mixture is generally solid or a thick paste, unless an amountof'acidhas been used in excess of that usually necessary. The digestion withthe sulfuric acid accordingly results in a selective extraction of theradium and barium compounds of the ore as sulfates, together with moreor less other constituents of the ore which are dissolved under theparticular conditions of treatment. The uranium and vanadium compoundsof the ore are converted into water soluble products. The greater partof the ore-thesands (silica and silicates)is not materi ally acted uponby the hot acid unless the digestion and boiling is quite prolonged. Theore-acid mass is next treated withwater without filtering ofl the acidsolution from themain body of the ore. To promote interaction andsolution, it has been. found par-' ticularly advantageous to add theore-acid mass to the water with stirring and agitation. The addition ofwater causes precipitation of the radium-barium sulfates in a veryfinely divided form, while most of the uranium and vanadium compounds,and more or less of the other water-soluble components, pass intosolution. The sands and silicates of the ore are, for the most part,relatively coarse grained, and settle quite rapidly when agitation ofthe liquor ceases,- while the fates, because of their fine state ofdivision, settle relatively slowly and remain for some time insuspension? above the sands which more rapidly settle out. In fact,after only a short period of finer ,lparticles, including theradium-barium su time, after the agitation of the solution has ceased, adistinct boundary appears between the sandy sediment and the supernatantliquid and suspension. The liquid with suspended matter is now run offand the radium-barium sulfates in suspension above the sediment isthereby separated from the ous types of agitators, and many. of themechanical devices used in the wet concentration of ores areavailable-for this purpose when constructed of suitable acid resistantmaterial.

In order to complete the removal of the finely divided material stillremaining in the sands after the first treatment with water, the sandscan with advantage be given several additional washings, preferably withwater containing a trace of barium salt, and the diiferentialsedimentation repeated as many times as may be necessary. The washingwith water and the removal of the water after a short period ofdifferential sedimentation, is usually repeated until the original deepblue color of the solution disappears step by step in the wash liquids.The washed sands, constituting the tailingsin this process, arepractically free from radium, rarely containing more than five per cent.of the radium 'content of low grade ores.

The. several wash liquids are united and well stirred to permit solutionof the sparingly soluble calcium sulfate, where this compound ispresent. The combined liquors and suspended matter are then allowed tostand for a suitable period of time, which may vary from one to three orfour days, to complete the precipitation-of the radiumbariumsulfates..The sediment or sludge thus obtained, when dried, constitutes. theradium concentrate.

The total quantity of water used will vary' somewhat with the nature ofthe ore, but in practice the volume of water is generally at least tentimes that of the acid used in the treatment of the ore. A somewhat morecomplete recovery of radium is obtained where the water used contains insolution a small quantity of some soluble barium salt.

The presence of barium .salts in the water prevents the radium-bariumsulfates from redissolving in part, as might be the case with water freefrom barium salts and hence capable of dissolving some small amounts ofbarium sulfate. The presence of barium sulfate in the water prevents theprecipitated radium-barium sulfates from being redissolved. Mostcarnotite ores contain sufficient barium compounds for the precipitationof radium, but where the ores are deficient in barium compounds, furtheramounts therein.

of barium salts can with advantage be added to increase the bariumsulfate which carries down the radium sulfate.

In order that the sand and gangue constituents of the ore may not be ina too finely divided form which might interfere with the extraction ofthe oreand the subsequent differential sedimentation, the ore should notbe crushed finer than is necessary to break up the ore particles andexpose the carnotite containing the radium. With sand-stone ores, suchas the usual carnotite ores, in which the carnotite for the most part isformed on the outside of the sand-stone granules, crushing 'to ten ortwenty mesh will usually be sufficient and will result in the productionof an ore body which lends itself readily to extraction and differentialsedimentation according to the present invention.

In treating the ore, it is sometimes desirable to start digestion withacid which is more dilute than Baum, or to conduct the digestion atlower temperatures. In order, however, to get a high extraction, thetreatment must be continued until the acid becomes more concentrated, e.g., until the temperature reaches 200 C. or higher. Thereby the processbecomes substantially the equivalent of the process in whichconcentrated acid is used at the outset. Small amounts of other acids,such as hydrochloric acid or nitric acid or sulfurous acid, may be addedto the sulfuric acid and may be present during the process, withoutmaterially impairing the process, and, in some instances, even withimproved results.

Instead of using sulfuric acid, concentrated solutions of the salt cake,or acid sodium sulfate, obtained as a by-product in the manufacture ofnitric acid from sodium nitrate, may be used. By continued boiling ofthe ore with such solutions, a similar extraction of the radium andbarium compounds as sulfates can be effected, while the advantages ofthe wet extraction with sulfuric acid are to a greater or less extentobtained.

Instead of using solutions of salt cake, the solid salt cake can be usedand heated to a suitable temperature to melt the cake and cause thedesired solution of the radium The digestion of the ore with salt cakefor the purpose of dissolving the radium and barium as sulfates isfinally conducted at somewhat higher temperatures than with sulfuricacid, 6. y., 360 C. or higher, and the digestion is continued for halfan hour or more and preferably for as much as an hour. If the mixture ofsalt cake and ore is allowed to cool, .it becomes solid and is thendiflicult to break up and get into solution. I have found, however, thatby suitably pouring the hot viscous liquid into water," preferably hotwater, and

stirring vigorously, the soluble portions of the ore pass into solutionreadily and the radium-barium. sulfates are precipitated and can beseparated with other suspensoids from the coarse sands in the mannerindi cated above. Extractions as high as 95% can be obtained. I

In adding either the hot sulfuric acid solution of the radium-bariumsulfates, or the concentrated salt cake solution or the molten salt cakesolution, to the water, as distinguished from first cooling and thenstirring the solid or thick pasty mass into water, the breaking up ofthe mass and the extraction of the soluble constituents withaccompanying precipitation of the radium-barium sulfates can be effectedin a particularly advantageous manner.

Instead of using concentrated sulfuric acid or salt cake for dissolvingthe radium from the ore, the more expensive hydrochloric acid of 30%concentration or higher may be used for digesting the ore. So also,nitric acid of 30% or stronger can be used instead of sulfuric, orsuitable mixtures of nitric and hydrochloric acids containing a total of30% or more of the acids. When these acids are used for digesting theore, the radium-barium sulfates are precipitated within the ore mass, asby dilution with water, and the addition of small amounts of sulfuricacid or soluble sulfates together with soluble salts or barium to preciitate further amounts of barium sulfate, W ere the product is too poorin barium sulfate to cause the desired carrying down of the radiumtherewith. 'From the resulting mixture, containing the precipitatedsulfates together with the sand, etc.', the sulfates are separated by adifferential sedimentation, in the manner above indicated.

In my prior application, Serial No. 52,485, filed September 2- 1, 1915,I have described and claimed a method of effecting a selectiveextraction of radium from carnotite ores and concentrates and othersuitable radium containing material, according to which the material istreated with concentrated sulfuric acid to dissolve out theradium-barium components as sulfates, and the radiumbarium sulfatessubsequently recovered, as by precipitation by adding water. The presentinvention relates to an improvement upon the method of said priorapplication according to which the carnotite ores are treated fortheproduction of concentrates, by a procedure in which the radium-bariumsulfates are precipitated in admixture with the undissolved material andseparated from the sand and other insoluble gangue constituents by adifferential sedimentation.

Instead of precipitating all of the dissolved radium-barium sulfates inadmixture with the undissolved material, part of the solution of thesulfates can be separated, as

by filtration, before precipitation, and the remainder precipitated, bydilution with water, in admixture with the undissolved residue, andrecovered by a differential sedimentation. The present inventionaccordingly enables the remaining portions of the dissolvedradium-barium sulfates to be recovered from admixture with the insolubleresidue, after part of the dissolved radiumbarium sulfates have beenotherwise separated, e. 9., by filtration.

The further concentration of the radium in the concentrates obtained bythe process of the present invention can be conducted by selectiveextraction with an excess of sulfuric acid and precipitation of theradiumbarium sulfates from the acid solution, sep arated from theinsoluble residue, by simple dilution with water, as described andclaimed in said prior application. The concentrates can, furthermore, befurther concentrated by fusion methods or by other suitable methods ofconcentration familiar to those skilled in the art.

The degree of extraction and concentration of the radium in the ore,according to the present invention, varies somewhat with different ores.The process, however, yields a high extraction'and recovery from lowgrade ores. Thus, in treating 50 pounds of low grade carnotitecontaining 1.7% of uranium oxid U 0 and 4.85 parts of radium perbillion, by digestion for about 15 minutes with 45- pounds of crudeconcentrated sulfuric acid of specific gravity 1.72, at a temperature of200 (1., a concentrate was obtained which, after being dried byignition, weighed 1.98 pounds. The radium content of the concentrate hasbeen increased to 112 parts per billion, which'represented a recovery ofabout 92% of the radium in the ore.

What I claim is:

1. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with a suitable solvent to dissolve the radium, together withbarium, as sulfates, diluting the resulting solution and therebyprecipitating the radium-barium sulfates in a finely divided conditionin admixture with the undissolved material, and separating the finelydivided radium-barium sulfates by a differential sedimentation.

2. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with a suitable solvent to dissolve the radium, together withbarium, as sulfates, diluting the resulting solution and therebyprecipitating the radium-barium sulfates in a finely divided conditionin admixture with the undissolved material, subjecting the resultingmixture to a differential sedimentation and thereby separatingtheradium-barium sulfates in the form of a concentrate, and repeating thedifferential sedimentation with water containing a barium salt toseparate further amounts of the radium-barium sulfates.

3. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises extractingthe radium with a suitable solvent, precipitating the dissolved radium,together with barium, as sulfates in admixture with the undissolvedmaterial, and subjecting the resulting mixture to a differentialsedimentation in a solution saturated with barium sulfate, and therebyseparating the radium-barium sulfates in the form of a concentratewithout solution of the radium.

4. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with concentrated sulfuric acid to dissolve the radium,

' together with barium, as sulfates, diluting radium barium sulfates ina finelyvdivided condition in admixture with the undissolved material,and separating the finely divided radium-barium sulfates by adifferential sedimentation.

6. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with hot concentrated sulfuric acid at a emperature of about200 'C. to dissolve the radium, to-

gether with barium, as sulfates, diluting the resulting solutionand'thereby precipitating the radium-barium sulfates in a finely dividedcondition in admixture with the undissolved material, and separating thefinely divided radium-barium sulfates bya differential sedimentation.

v7. The method of producing radium con centrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with concentrated sulfuric acid to dissolve the radium,together with barium, as sulfates, diluting the resulting solution withwater containing barium salts and thereby precipitating theradium-barium sulfates in a finely divided condition in admixture withthe undissolved material, and separating the finely dividedradium-barium sulfates by a differential sedimentation.

8. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises extractingthe radium with a suitable solvent, precipitating the dissolved radium,together with barium, as sulfates in admixture with the undissolvedmaterial, and subjecting the resulting mixture to a differentialsedimentation in a solution saturatedwith barium sulfate and containingsuflicient water to dissolve small amounts of calcium sulfate, andthereby separating the radiumbarium sulfates in the form of aconcentrate substantially free from calcium sulfate without solution ofthe radium sulfate.

9. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with concentrated sulfuric acid to dissolve the radium,together with barium, as sulfates, diluting the resulting solution withan amount of Water sufficient to dissolve small amounts of calciumsulfate present and thereby precipitating the radium-barium sulfatessubstantially free from calcium sulfate in a finely divided condition inadmixture with the undissolved material, and separating the finelydivided radium-barium sulfates by differential sedimentation.

10. The method of producing radium concentrates from carnotite ores andother suit able radium containing material which comprises boiling thematerial with dilute sulfuric acid until an acid of about 60.B. isproduced to dissolve the radium, together with barium, as sulfates,diluting the resulting solution and thereby precipitating theradium-barium sulfates in a finely divided condition in admixture withthe undissolved material, and separating the finely dividedradium-barium sulfates by a differential sedimentation.

11. The method of producing radium concentrates from carnotite ores andother suitable radium containing material, which comprises treating thematerial with concentrated sulfuric acid to dissolve the radium,

together with barium, as sulfates, diluting the resulting solution andthereby preclpitating thera'dium-barium sulfates in a finely dividedcondition in admixture with the undisolved material, and separating thefinely divided radium-barium sulfates from the undissolved, material.

12. The method of producingradium concentrates from carnotite ores andother suit able radium containing material, which comprises treating thematerial with concentrated sulfuric acid to dissolve the radium,together with barium, as sulfates, separating part. of the resultingsolution from the ing solution and undissolved materiel, diluting the"remainthereby precipitating there-xfrom theradium-bariufii sulfates, ina; finely I in admixture withithe undissolved .material, and separatingthe finely divided radium berium' sulfates 'frorn "the undissolvedmaterial. 1 v. 13. The method of producing radium con; I centrates fromcarnotlte ores and other suitdivided condition,

able ra(hum-containing meteriahr which comprises treating the materielag' 'su iti ite'rial', Y and separating with barium, es sulfates,pouring the resulting solution into water and thereby the solution andprecipitating the radiumbarium sulfates inf a, finely-divided conditionin admixturefwith' the undissolved mathe finely divided redium beriumsulfates from the undissolved material. F In testimony whereof I afiixmy signature.

SCHLUNDT.

. a time solteut to (ifs-salve the radium, together diluting

